To enhance participant recruitment efforts for genetics studies and other large- scale etiological research efforts, there is a need for an instrument that can be practically and efficiently employed in research studies of autism spectrum disorders (ASD). The current proposal aims to develop a research screening instrument that is based on questions from the Autism Diagnostic Interview-Revised (ADI-R;Rutter et al., 2003), but that is substantially shorter and easier to administer. The newly developed ADI Research Screening Interview will be appropriate for use in person or on the telephone. Development of the ADI Research Screening Interview will involve two large samples of children with ASD and non-ASD diagnoses. Existing data from a total of 979 assessments of children with ASD and 257 assessments of children with non-ASD diagnoses will be used to develop the instrument. A separate group of approximately 180 participants with ASD and 240 with non-ASD diagnoses will be recruited from ongoing research studies and specialty diagnostic clinics to test the new measure. Given recent findings that children with certain non-ASD diagnoses are often misclassified by ASD screening and diagnostic measures (e.g., Towbin et al., 2005;Bishop, et al., 2007), a particular strength of this proposal is the recruitment of children with targeted non-ASD diagnoses, including intellectual disability (ID), attention deficit hyperactivity disorder (ADHD), anxiety disorder, and an early developmental risk group. With the advent of new technologies making genetic testing more accessible and less expensive, researchers are increasingly calling for a way to rapidly screen large populations for ASD first, and then carry out more intensive phenotyping after genetic tests are analyzed. The availability of a diagnostic screening instrument with high levels of sensitivity and specificity will dramatically reduce the time and expense that is currently required to determine diagnostic status of ASD research participants. The option of administering the screening protocol by telephone will facilitate access to more diverse participant populations for whom travel may be less feasible and who are traditionally under-represented in ASD research. PUBLIC HEALTH RELEVANCE: This proposal will result in the development of a new screening instrument to identify children with autism spectrum disorders (ASD). Several investigations are currently underway in order to better understand the causes of ASD. Many of these studies require very large numbers of participants;however, current methods for identifying participants for such studies are often expensive and time-consuming and require intensive training. To address these issues, we aim to create a short parent interview that can be administered on the telephone to quickly identify potential participants for ASD research. This new instrument will facilitate research into ASD etiology by increasing the speed and effectiveness of participant recruitment efforts. In addition, such an instrument may have other practical uses clinically. In communities where the wait for an ASD evaluation is extremely long or there are no local resources for diagnostic evaluations, an efficient screening instrument that could be administered by phone might help triage children in need of further evaluation and/or be used to qualify children for certain intervention services pending a more complete diagnostic evaluation at a later time.